Fermentation optimization of naringinase from a screened strain of Serratia marcescensC10 through response surface methodology

In this study, for the first time, we isolated a naringinase-producing strain from the Citrus aurantium L. var. amaraEngl flower soil and identified it as Serratia marcescensC10. In order to improve naringinase activity for its industrial application, single-factor experiments were carried out to obtain the factors that greatly affect naringinase activity, and based on three factors and three levels of Box-Behnken Designs (BBD), response surface methodology (RSM) was used to optimize the culture conditions consisting of naringin concentration, inoculation size and fermentation time. Results showed that naringin concentration and fermentation time had a highly significant influence and significant influence on naringinase activity, respectively. Additionally, inoculation size and fermentation time had an interaction with naringinase activity. The optimized conditions were a naringin concentration of 0.09 mg/mL, an inoculation size of 5.5%, and a fermentation time of 60 h. Under optimal culture conditions, the experiment naringinase activity was 30.81 U/mL, which was close to the predicted theoretical value of 31.23 U/mL. The optimized naringinase was used to remove naringin in grapefruit juice, and the removal rate was 88.85% under optimal reaction conditions.